The invention relates to a method for fabricating a flat, light-emitting display panel having electrodes extended from a rear panel and sealing the margin of panels with a fritted glass.
Generally, it is difficult to construct a large-screen monitor including only one display panel (hereafter, referred to as xe2x80x9cpanelxe2x80x9d) due to various technical reasons and the need to reduce cost. Therefore, multiple panels are tiled to form a large-screen monitor.
In a case where no-display area at ends of each panel is large, seams are formed between the adjacent panels and as a result, an image quality of the large-screen as a whole is reduced significantly. Therefore, it is desirable to develop a flat light-emitting display panel with smaller no-display area at ends of each panel in order to display a high quality image on a large-screen monitor.
The applicants previously propose a structure of the flat, light-emitting display panel formed from a matrix of the plural panels to fit such a need.
FIG. 1 is a cross sectional view of a side-seal structure of the flat light-emitting display panel (hereafter, referred to as xe2x80x9cdisplay panelxe2x80x9d) disclosed in the previous, co-pending application. In the drawing, a reference numeral 1 denotes a transparent front panel. A reference numeral 2 denotes a rear panel, which is arranged in parallel with the front panel 1 and has a plurality of recesses 2a. Each recess 2a is defined as a discharging space for a display cell. Although not shown in FIG. 1, FIG. 4 illustrates a display cell which is marked by reference numeral 21. An electrical insulating glass layer (not shown) is formed at a bottom face and an inner wall of each recess 2a of the rear panel 2. A fluorescent substance 3 is applied on the electrical insulating glass layer. A pin electrode (not shown) penetrating the rear panel 2 is arranged within the front panel 1. A pair of cell-type electrodes (not shown) is positioned corresponding to the recess 2a of the rear panel 2. Although not shown in FIG. 2, FIGS. 4 and 5 illustrate a pair of cell-type electrodes which is marked by reference numeral 20 and a pin electrode which is marked by reference numeral 6, respectively.
With such a constructed display panel, in order to reduce the no-displayed area in ends of display panel, the pin electrode 6 connecting with the electrode arranged at the front panel 1 is extended from the rear panel. The size of the front panel 1 is set to a value larger than that of the rear panel 2. A frit seal 4 is applied to an extended area 1a of the front panel 1 that extends off the rear panel 2 and to a side face 2b of the rear panel 2 and burned. As a result, the gap of the front panel 1 and the rear panel 2 is sealed.
Next, a method for fabricating a display panel will be explained in order of undergoing process.
(Step 1)
A transparent electrode (not shown) including a discharging gap is formed at the front panel 1 using an ITO (indium-tinned oxide) or a Nesa (tinned oxide), for example.
(Step 2)
Electric terminals are formed at one end of the transparent electrode (not shown) formed in the previous step 1 by a screen printing method using conductive materials such as an Ag or silver and so on.
(Step 3)
Electrical insulating glass layers (not shown) are formed at the whole of the front panel 1 except for the electric terminals (not shown) formed in the step 2.
(Step 4)
Pin electrodes (not shown) are projected in the electric terminals (not shown), respectively.
(Step 5)
A MgO film is formed on the electrical insulating glass layer (not shown) formed in the previous step 3 to finish all processes regarding the front panel 1.
(Step 6)
Recesses 2a, which are defined as a through-hole for passing through the pin electrode (not shown) and functioned as a discharging space for a display cell, are formed at the rear panel 2 using a sandblasting method and so on.
(Step 7)
Fluorescent substance (R: red, G: green, B: blue) 3 is applied to the bottom face and the inner wall of the recess 2a formed in the previous step 6 using the screen printing method and so on to finish all processes regarding the rear panel 2.
(Step 8)
Each of the pin electrodes (not shown) projected at the front panel 1 is fitted into each of the through-hole (not shown) of the rear panel 2. The rear panel 2 is stacked to the front panel 1 so that the fluorescent substance 3 faces the front panel 1.
(Step 9)
Ends of the front panel 1 and those of the rear panel 2 having no pin electrodes are stacked and fixed using a spring-loaded clip (not shown).
(Step 10)
A frit seal is applied to the pin electrode (not shown) using a dispenser (not shown).
(Step 11)
After the frit seal 4 applied in the previous step 10 is dried, the spring-quipped clip (not shown) is removed. The frit seal 4 is applied to a pipe-shaped, tipped section (not shown) and an outer periphery of the panel, that is, the extended area 1a of the front panel 1 and the side face 2b of the rear panel 2 using the dispenser (not shown).
(Step 12)
Weights (not shown) is placed at a part other than the pipe-shaped, tipped section (not shown) and the pin electrode (not shown) and the frit seal 4 is then burned. Air is exhausted from a space between the panels and discharge gas is filled and sealed in the space.
(Step 13)
The MgO adhered to the pin electrode (not shown) is removed using a sandblasting method and so on. In this way, a display panel is obtained.
When plural display panels, which are fabricated by the processes as described above and disclosed in the previous application, are arranged, lighted and displayed, there may be case where a display gap is formed between adjacent panels.
The present inventors investigated adequately the cause of gap in the display panel and found that a frit seal, which is formed at the extended area 1a of the front panel 1 and the side face 2b of the rear panel 2, is spread into the display cell. Namely, when the fluorescent substance 3 applied to the rear panel 2 or an area of the front panel 1 corresponding to the fluorescent substance 3 is covered with the frit seal spread into the display cell, light is not emitted or cut off from the covered section. Therefore, it results in no-emitting area or no-displayed area being increased at the ends of the display panel. The no-emitting area is considered to seem like a gap between adjacent panels.
A gap between the front and rear panels 1 and 2 when the frit seal 4 is applied to the extended area 1a of the front panel 1 and the side face 2b of the rear panel 2 is considered to become a cause of spread of the frit seal. In the step 11, the spring-loaded clip (not shown) is removed and a distance of a gap between the front panel 1 and the rear panel 2 is measured using a gap-measurement gage (not shown) before the gap is sealed with the frit seal. As a result, a gap of approximately 0.15 mm was found. When a large-sized gap is formed at the gap, the frit seal 4 is applied thereto to result in the frit seal 4 in a large amount being inserted into the gap. The frit seal 4 is burned in the step 12 to result in a softened frit seal 4 in a large amount being inserted into the cell.
Such a gap is formed due to warping of the front and the rear panels 1, 2, causing the front and the rear panels to be convex as shown in FIG. 3. The electrical insulating glass layer (not shown) is approximately 30 um in thickness is formed on a surface of the front panel 1. For example, when the ends of the both front and rear panels 1, 2 are cramped using the spring-loaded clip 5 as shown in FIG. 3, the distance between the central sections of the panels 1, 2 becomes larger compared to the end sections of the panels 1, 2. In order to prevent warping of the panels 1, 2, the pin electrodes located on the central section must be fixed provisionally using the frit seal 4. Next, in order to apply the frit seal 4 to the extended area 1a of the front panel 1 and the side face 2b of the rear panel 2, the spring-loaded clip 5 is removed. Further, this causes the gap to be formed between the ends of the panels 1, 2 as shown in FIG. 2.
Furthermore, the following other factors are considered to become a cause of the spread of the frit seal. That is, the frit seal 4 is softened at the side of the front panel 1 and the rear panel 2 on burning to pass through a micro-gap between the front and rear panels 1 and 2 by capillary action toward the cell. In order to decrease the spread of the frit seal, the flowability of the frit seal 4 must be set to become a small value on softening. Therefore, we have learned that the frit seal 4 must be burned on condition that the burning is performed at a low temperature or for a short time.
However, when the frit seal 4 is burned on such a condition, reduction of the spread of the frit seal 4 into the cell can occur. When a voltage is applied to the display panel, there are malfunctions that discharge occurs abnormally at the pin electrodes. There is a reason: when the frit seal 4 is burned on the condition above, the frit seal 4 having a low flowability can not flow adequately into the pin electrode. The pin electrode is coated inadequately with the frit seal 4 and the insulating properties are reduced. As a result, the discharge occurs abnormally when the voltage is applied to the display panel.
On the other hand, in order to coat perfectly the pin electrode, it is necessary to burn the frit seal 4 at a high temperature or for a long time. In such a case, there is a malfunction that the softened frit seal 4 applied to the ends of the panel is spread into the cell. That is, the coating of the pin electrode and the spreading of the frit seal applied to the ends of the panel are mutually contradictory and it is difficult to maintain compatibility between both sides.
The invention was made to solve the foregoing problems. Accordingly, it is an object of the invention to provide a method for fabricating a flat, light-emitting display panel that a pin electrode can be coated perfectly with a frit seal and that reduction of the spread of the frit seal into a cell can occur.
In order to achieve the object of the invention, we provide a method for fabricating a flat, light-emitting display panel including a transparent, front panel, a rear panel arranged in parallel to the front panel and having a plurality of recesses, each recess being defined as a discharging space for a display cell, a pin electrode projected inwardly in a state of penetrating the rear panel, and a pair of cell-type electrodes, which works at the presence of voltage from the pin electrodes, arranged at every area of the front panel facing each of the recesses of the rear panel, wherein the method comprises the steps of: applying frit seal to the pin electrodes in a state of pressing the rear panel against the front panel to keep them in contact with one another using a flat plate having an opening formed at a position corresponding to each of the pin electrodes; drying the frit seal to fix provisionally the rear panel to the front panel; detaching the flat plate from the both panels; applying frit seal to an end of the front panel and a side face of the rear panel; and burning the whole of components. In this way, both of the panels are fixed provisionally on condition that the panels are kept uniformly in contact with one another using the flat plate. In this way, it is possible to prevent a gap formed between both of the panels due to their warping and to prevent the frit seal from spreading into the gap between both of the panels. Moreover, it is unnecessary to vary conditions for burning the frit seal. The frit seal is therefore burned on condition that the pin electrodes 6 can be coated adequately.
With the above arrangement, the method may comprise the steps of: placing both of the front panel and the rear panel stacked to the front panel on a base plate having a flat face; and securing the flat plate to the base plate by screws. In this way, the front panel and the rear panel are sandwiched between the flat plate and the base plate to keep the both panels in contact with one another. It is therefore possible to reliably prevent the spread of the frit seal into the gap between the both panels on application of the frit seal and on burning.
With the above arrangement, the method may comprise the steps of: placing both of the front panel and the rear panel stacked to the front panel on a base plate having a flat face; and securing the flat plate to the base plate by screws through a plurality of biasing means. In this way, the front panel and the rear panel are sandwiched between the flat plate and the base plate to keep the both panels in contact with one another. It is therefore possible to reliably prevent the spread of the frit seal into the gap between the both panels on application of the frit seal and on burning.
With the above arrangement, the frit seal, which is applied to the end of the front panel and the side face of the rear panel, may have flowability less than the frit seal applied to the pin electrodes. In this way, it is possible to reduce the amount of the frit seal, which spreads from the margins of the both panels into the gap, to the minimum level.
We provide a method for fabricating a flat, light-emitting display panel including a transparent, front panel, a rear panel arranged in parallel to the front panel and having a plurality of recesses, each recess being defined as a discharging space for a display cell, a pin electrode projected inwardly in a state of penetrating the rear panel, and a pair of cell-type electrodes, which works at the presence of voltage from the pin electrodes, arranged at every area of the front panel facing each of the recesses of the rear panel, wherein the method comprises the steps of: applying frit seal to an end of the front panel and a side face of the rear panel in a state of pressing the rear panel against the front panel to keep them in contact with one another using a flat plate having an opening formed at a position corresponding to each of the pin electrodes; drying the frit seal to fix provisionally the rear panel to the front panel; detaching the flat plate from the both panels; applying frit seal to the pin electrodes; and burning the whole of components. In this way, both of the panels are fixed provisionally on condition that the panels are kept uniformly in contact with one another using the flat plate. In this way, it is possible to prevent a gap formed between both of the panels due to their warping and to prevent the frit seal from spreading into the gap between both of the panels. Moreover, it is unnecessary to vary conditions for burning the frit seal. The frit seal is therefore burned on condition that the pin electrodes 6 can be coated adequately.
With the above arrangement, the method may comprise the steps of: placing both of the front panel and the rear panel stacked to the front panel on a base plate having a flat face; and securing the flat plate to the base plate by screws. In this way, the front panel and the rear panel are sandwiched between the flat plate and the base plate to keep the both panels in contact with one another. It is therefore possible to reliably prevent the spread of the frit seal into the gap between the both panels on application of the frit seal and on burning.
With the above arrangement, the method may comprise the steps of: placing both of the front panel and the rear panel stacked to the front panel on a base plate having a flat face; and securing the flat plate to the base plate by screws through a plurality of biasing means. In this way, the front panel and the rear panel are sandwiched between the flat plate and the base plate to keep the both panels in contact with one another. It is therefore possible to reliably prevent the spread of the frit seal into the gap between the both panels on application of the frit seal and on burning.
With the above arrangement, the frit seal, which is applied to the end of the front panel and the side face of the rear panel, may have flowability less than the frit seal applied to the pin electrodes. In this way, it is possible to reduce the amount of the frit seal, which spreads from the margins of the both panels into the gap, to the minimum level.